Method for manufacturing a battery cell in a rechargeable energy storage system

Abstract

A method for forming a battery cell in a rechargeable energy storage system comprises providing a cathode and an anode, the cathode containing a lithium metal phosphate. The method includes positioning a separator between the cathode and the anode, the separator having a side facing the anode and a side facing the cathode. The method includes depositing a catalyst layer, consisting of an oxygen storage catalyst, onto the cathode-facing side of the separator such that the catalyst layer continuously covers the cathode-facing side of the separator. The oxygen storage catalyst has an oxygen uptake capacity at or above a threshold temperature, and the oxygen storage catalyst has an oxygen retention capacity at or above the threshold temperature, the threshold temperature being at least 200 degrees Celsius.

Description

[0001] This description relates to a rechargeable energy storage system with a battery cell whose separator is coated with an oxygen storage catalyst, and to a corresponding method for manufacturing the battery cell. The use of mobile platforms that utilize a rechargeable energy source, both as the sole and a secondary energy source, has increased significantly in recent years. A rechargeable energy storage device with battery packs can store electrochemical energy and release it as needed in a specific operating mode. This electrochemical energy can be used for propulsion, heating or cooling the vehicle interior, powering vehicle accessories, and for other purposes. The various cells within the battery packs can be characterized by different power ratings, states of charge, and capacities.Many batteries use a separator to prevent physical contact between the cathode and anode while still promoting the movement of ions between them. The challenge in developing battery separators lies in finding a compromise between mechanical robustness and porosity / transport properties.

[0002] JP 2014 211 978 A describes a composite electrode for a lithium-ion secondary battery, comprising: an oxygen-releasing active material selected from positive electrode materials containing a lithium metal oxide and exhibiting the property of releasing oxygen with increasing temperature; and an oxygen-absorbing material selected from the positive electrode materials exhibiting the property of adsorbing oxygen with increasing temperature; wherein the oxygen release temperature range of the oxygen-releasing active material and the oxygen adsorption temperature range of the oxygen-adsorbing active material overlap at least partially.

[0003] The task can be considered to be to specify an improved method for manufacturing a battery cell in a rechargeable energy storage system.

[0004] This document describes a method according to the invention for manufacturing a battery cell in a rechargeable energy storage system. The method comprises providing a cathode and an anode, the cathode containing a lithium metal phosphate. The method includes positioning a separator between the cathode and the anode, the separator having a side facing the anode and a side facing the cathode. The method includes applying a catalyst layer, consisting of an oxygen storage catalyst, to the cathode-facing side of the separator, such that the catalyst layer continuously covers the cathode-facing side of the separator.The oxygen storage catalyst has an oxygen uptake capacity at or above a threshold temperature, the oxygen storage catalyst has an oxygen retention capacity at or above the threshold temperature, and the threshold temperature is at least 200 degrees Celsius.

[0005] In one embodiment, the method comprises setting the threshold temperature to 250 degrees Celsius. In another embodiment, the method comprises selecting a catalyst layer thickness between 0.1 nanometers and 100 nanometers. In another embodiment, the method comprises incorporating a [LiFe] configuration. x Mn 1-xPO4] into the lithium metal phosphate of the cathode, where Li represents lithium, Fe represents iron, Mn represents manganese, P represents phosphorus, and O represents oxygen. In one embodiment, the method comprises selecting the oxygen storage catalyst to have a perovskite structure [ABO3], where A and B are cations and O is oxygen. In another embodiment, the method comprises selecting the oxygen storage catalyst to contain cerium oxide [CeO2], where Ce represents cerium and O represents oxygen.

[0006] In one embodiment, the method comprises depositing a bonding layer between the cathode and the catalyst layer, wherein the bonding layer consists at least partially of polyvinylidene fluoride. In another embodiment, the method comprises depositing the catalyst layer on the cathode-facing side of the separator by atomic layer deposition, wherein the separator consists at least partially of polyethylene. In yet another embodiment, the method comprises depositing the catalyst layer on the cathode-facing side of the separator by chemical vapor deposition.

[0007] The method according to the invention enables the production of a rechargeable energy storage system. This system comprises one or more battery cells, each having an anode and a cathode. The cathode contains a lithium metal phosphate. A separator is arranged between the anode and the cathode, having a side facing the anode and a side facing the cathode. The cathode-facing side of the separator is continuously coated with a catalyst layer consisting of an oxygen storage catalyst. The oxygen storage catalyst has an oxygen uptake capacity at or above a threshold temperature, which is at least 200 degrees Celsius. The oxygen storage catalyst also has an oxygen retention capacity at or above the threshold temperature.

[0008] An energy storage system produced according to the inventive method can be installed in a vehicle. The vehicle with the rechargeable energy storage system, comprising one or more battery cells, each having an anode and a cathode, is described below. The cathode contains a lithium metal phosphate. A separator is arranged between the anode and the cathode, having a side facing the anode and a side facing the cathode. A catalyst layer continuously covers the cathode-facing side of the separator, the catalyst layer consisting of an oxygen storage catalyst and having a thickness between 0.1 nanometers and 100 nanometers. A bonding layer continuously covers the catalyst layer, the bonding layer being located between the cathode and the catalyst layer.The oxygen storage catalyst has an oxygen uptake capacity at or above a threshold temperature, which is 250 degrees Celsius. The oxygen storage catalyst also has an oxygen retention capacity at or above this threshold temperature. Fig. Figure 1 is a schematic, fragmentary diagram of a rechargeable energy storage system with a large number of battery cells; Fig. Figure 2 is a schematic flowchart of a process for manufacturing battery cells from Fig. 1; and Fig. Figure 3 is a schematic fragment diagram showing an alternative battery cell structure used in the rechargeable energy storage system of Fig. 1 can be used.

[0009] Fig. Figure 1 schematically shows a rechargeable energy storage system 10 designed to power a vehicle 12, where identical reference numbers refer to identical components. The vehicle 12 can be partially or fully electric. The vehicle 12 can be a mobile platform, such as a passenger car, a sport utility vehicle, a light truck, a heavy-duty vehicle, an ATV, a minivan, a bus, a transit vehicle, a bicycle, a self-driving robot, agricultural equipment (e.g., a tractor), sports equipment (e.g., a golf cart), a boat, an aircraft, or a train. It is understood that the vehicle 12 can take many different forms and have additional components.

[0010] The rechargeable energy storage system 10 comprises at least one battery module 14 with a variety of lithium-ion battery cells, such as those in Fig. 1 Battery cell 16 shown, which is connected for current flow between a first terminal 18A and a second terminal 18B. It is understood that the number of battery modules in the rechargeable energy storage system 10, as well as the number of battery cells in each of the modules, can be varied based on the specific application.

[0011] In Fig. Figure 1 shows an example of the construction of battery cell 16. The battery cell 16 comprises a cathode 20 and an anode 22, which are arranged between a first current collector 24 and a second current collector 26. A separator 30 is arranged between the cathode 20 and the anode 22. It should be understood that the figures shown here are not drawn to scale. The separator 30 promotes the movement of ions from the cathode 20 to the anode 22 during charging and the reverse flow during discharging. The separator 30 is an insulator without electrical conductivity.

[0012] The separator 30 can be directly moistened with a first electrolyte layer 32 on one of the anode 22 adjacent to the anode 22 on the side 34 of the separator 30 facing the anode. As in Fig. As shown in Figure 1, the separator 30 can be directly moistened with a second electrolyte layer 36 on the side 38 facing the cathode 20.

[0013] The battery cells 16 can have different chemistries, including, but not limited to, lithium-ion and lithium iron phosphate (LFP) batteries. The battery cell 16 can have a [LiFe] configuration. x Mn 1-x The lithium metal phosphate cathode contains LiMPO4, where Li is lithium, Fe is iron, Mn is manganese, P is phosphorus, and O is oxygen. Other materials available to those skilled in the art may be used. The cathode 20 can consist of lithium metal phosphates such as LiMPO4 [M: Fe, Mn, Co]. In some embodiments, lithium iron phosphate (LiFePO4) is used as the cathode material together with a graphite carbon electrode with a metallic substrate as the anode.

[0014] In lithium iron phosphate (LFP) batteries, oxygen gas released from the cathode 20 can flow through the separator 30, leading to side reactions at the anode 22 and triggering thermal runaway. Thermal runaway occurs when a single cell enters thermal runaway, releasing a large amount of heat and heating adjacent cells to the point of thermal runaway. Thermal runaway in a battery cell 16 is generally only detected after it has occurred. Additionally, the separator 30 can shrink at high temperatures.

[0015] The rechargeable energy storage system 10 mitigates thermal discharge events through the strategic placement of oxygen-trapping materials within the battery cells. Furthermore, the rechargeable energy storage system 10 improves the separator's stability at elevated temperatures and the electrolyte's wettability. The separator 30 is coated with an oxygen storage catalyst, which enhances both the thermal and mechanical stability (bifunctional) of the battery cell 16. As described below and with reference to Fig. 1, the battery cell 16 comprises a catalyst layer 40 which continuously coats the side 38 of the separator 30 facing the cathode, wherein the catalyst layer 40 consists of an oxygen storage catalyst (OSC).

[0016] The oxygen storage catalyst is selected such that it has an oxygen uptake capacity at or above a threshold temperature, wherein the threshold temperature is at least 200 degrees Celsius. In some embodiments, the threshold temperature is approximately 250 degrees Celsius. The oxygen storage catalyst is selected such that it has an oxygen retention capacity at or above the threshold temperature.

[0017] According to Fig. 1. The rechargeable energy storage system 10 can be operationally connected to a controller C with at least one processor P and at least one memory M (or a non-volatile, tangible, computer-readable storage medium) in which instructions are recorded. The memory M can store instruction sets executable by the controller, and the processor P can execute the instruction sets executable by the controller stored in the memory M.

[0018] In Fig. Figure 2 is a flowchart of process 100 for manufacturing battery cell 16 from Fig. Figure 1 shows the procedure. Procedure 100 can be executed as computer-readable code or as instructions issued on the controller C of Fig. The data is stored in step 1 and can be partially executed from it. Procedure 100 does not have to be applied in the order specified here. Furthermore, some steps can be omitted.

[0019] In block 102 of Fig. In section 2, process 100 comprises providing a cathode 20 and an anode 22 and arranging a separator 30 between the cathode 20 and the anode 22. In section 104, process 100 comprises selecting a set of oxygen storage catalyst materials and verifying the set with respect to various parameters, such as adsorption capacity, availability, and other factors. Adsorption is the ability of solid materials to attract fluid molecules to their surface when they are in close proximity.

[0020] Method 100 comprises screening the set of oxygen storage catalyst materials for their respective "oxygen uptake capacity" at or above a threshold temperature. The threshold temperature is at least 200 degrees Celsius. In some embodiments, the threshold temperature is approximately 250 degrees Celsius. In other words, if the oxygen storage catalyst material is unable to capture oxygen molecules at or above the threshold temperature, the oxygen storage catalyst material is removed from the set. The screening can be performed using differential scanning calorimetry, in which the difference in the amount of heat required to raise the temperature of a sample and a reference is measured as a function of temperature. Both the sample and the reference are maintained at nearly the same temperature throughout the entire process.

[0021] In the further course of Block 106, Method 100 comprises screening the set of oxygen-storing catalyst materials for their respective oxygen retention capacity at or above the threshold temperature. In other words, if the oxygen-storing catalyst material is unable to retain the oxygen molecules at or above the threshold temperature, the oxygen-storing catalyst material is removed from the set. In some embodiments, the oxygen-storing catalyst is selected to have a perovskite structure [ABO3], where A and B are cations and O is oxygen. Examples of such materials are La x MO3 (M =Co, Mn and Ni; x = 0.7 - 1.1), La 1-y Sr y MO3 (M = Co, Mn and Ni; y = 0 - 0.8), doped calcium manganite (CaB x Mn 1-x O 3-δ , where B = Ti, Al, Sr), La x Sr 1-x Co y M 1-y O 3-δ(M = Mn) and SCFC-based oxygen sorbents (Sr 1-x Approx x Fe 1-y Co y O 3-δ ).

[0022] In some embodiments, the oxygen storage catalyst is selected to contain cerium oxide [CeO2], where Ce represents cerium and O represents oxygen. Examples of such materials are pure CeO2, CeO2-ZrO2 solid solution, CeO2-MnO2, CeO2-CuO, CeO2-Fe2O3 solution, CeO2-based materials doped with PGMs (Pt, Pd, and Rh), and cerium oxide doped with other metals such as Sr, Pr, Sn, Tb, and Ti.

[0023] In block 108, process 100 deposits the catalyst layer 40 onto the cathode-facing side 38 of the separator 30, such that the catalyst layer 40 continuously coats the cathode-facing side 38 of the separator 30 with oxygen-trapping materials. The catalyst layer 40 can be deposited using various methods, such as atomic layer deposition, in which successive layer deposition occurs through repeated exposure to precursor substances. The catalyst layer 40 can be deposited by spray drying, in which an atomized liquid is applied as a fine spray, followed by contact with a hot air stream to remove the solvent. The catalyst layer 40 can also be deposited by the deposition of chemical vapors.

[0024] In the further course of block 110, the process 100 comprises the application of a bonding layer 242, which is designed to improve the adhesion of the catalyst layer 240 to the separator 230, an example of which is shown in Fig. 3 is shown. Fig. Figure 3 is a schematic, fragmentary diagram illustrating an alternative battery cell structure that can be used in the rechargeable energy storage system 10. The binder layer 242 can consist at least partially of polyvinylidene fluoride. The binder layer 242 can be injected or molded into the cell structure between the cathode 220 and the catalyst layer 240. Other methods available to those skilled in the art may be used. The cell structure may include a second electrolyte layer 236 between the cathode 220 and the separator 230, as well as other components not shown.

[0025] In summary, the rechargeable energy storage system 10 enables the prevention and early mitigation of thermal runaway situations. The separators 30 and 230 with the catalyst layer 40 and 240, respectively, lead to improved mechanical and thermal stability as well as improved wettability of the electrolyte. The mechanical stability and electrochemical properties of the separators 30 and 230 with the coating materials can be evaluated using computational methods, thus enabling an effective and targeted selection of the most suitable materials.

[0026] Procedure 100 can be executed dynamically. As used here, the terms "dynamic" and "dynamic" describe steps or processes that are executed in real time and are characterized by the fact that the states of parameters are monitored or otherwise determined, and the states of the parameters are updated regularly or periodically during the execution of a routine or between iterations of the routine's execution.

[0027] The control C of Fig.1. A computer-readable medium (also called a processor-readable medium) includes a non-volatile (e.g., tangible) medium involved in providing data (e.g., instructions) that can be read by a computer (e.g., by a computer's processor). Such a medium can take many forms, including, but not limited to, non-volatile and volatile media. Non-volatile media include, for example, optical or magnetic disks and other permanent storage devices. Volatile media include, for example, dynamic random-access memory (DRAM), which can constitute main memory. Such instructions can be transmitted over one or more transmission media, including coaxial cable, copper wire, and fiber optic cable, including the lines that comprise a system bus connected to a computer's processor.Some forms of computer-readable media include, for example, a floppy disk, a flexible disk, a hard disk, a magnetic tape, another magnetic medium, a CD-ROM, a DVD, another optical medium, a physical medium with hole patterns, a RAM, a PROM, an EPROM, a FLASH EEPROM, another memory chip, or a cartridge or other medium from which a computer can read.

Claims

[1] Method (100) for manufacturing a battery cell (16) in a rechargeable energy storage system (10), wherein the method (100) comprises: Providing a cathode (20) and an anode (22), wherein the cathode (20) contains a lithium metal phosphate; Positioning a separator (30) between the cathode (20) and the anode (22), wherein the separator (30) has a side (34) facing the anode (22) and a side (38) facing the cathode (20); and Applying a catalyst layer (40) consisting of an oxygen storage catalyst to the side (38) of the separator (30) facing the cathode (20), such that the catalyst layer (40) continuously covers the side (38) of the separator (30) facing the cathode (20), wherein the oxygen storage catalyst has an oxygen capture capability at or above a threshold temperature, the oxygen storage catalyst has an oxygen retention capability at or above the threshold temperature, and the threshold temperature is at least 200 degrees Celsius. [2] Method (100) according to claim 1, further comprising: Select a threshold temperature of 250 degrees Celsius. [3] Method (100) according to claim 1, further comprising: Adjusting the thickness of the catalyst layer (40) between 0.1 nanometers and 100 nanometers. [4] Method (100) according to claim 1, further comprising: Installing a [LiFe] configuration x Mn 1-x PO4] into the lithium metal phosphate of the cathode (20), where Li stands for lithium, Fe for iron, Mn for manganese, P for phosphorus and O for oxygen. [5] Method (100) according to claim 1, further comprising: Selecting the oxygen storage catalyst to enclose a perovskite structure [ABO3] where A and B are cations and O is oxygen. [6] Method (100) according to claim 5, further comprising: Selecting the oxygen storage catalyst to enclose cerium oxide [CeO2], where Ce stands for cerium and O for oxygen. [7] Method (100) according to claim 1, further comprising: Application of a binder layer (242) between the cathode (20) and the catalyst layer (40), wherein the binder layer (242) consists at least partially of polyvinylidene fluoride. [8] Method (100) according to claim 7, further comprising: The catalyst layer (40) is applied to the side (38) of the separator (30) facing the cathode (20) by atomic layer deposition, wherein the separator (30) consists at least partially of polyethylene. [9] Method (100) according to claim 7, further comprising: Deposition of the catalyst layer (40) on the side (38) of the separator (30) facing the cathode (20) using chemical vapor deposition, wherein the separator (30) consists at least partially of polyethylene.

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